path: root/src/gui/math3d/qmatrix4x4.cpp
diff options
authorGiuseppe D'Angelo <>2021-01-17 19:19:39 +0100
committerQt Cherry-pick Bot <>2021-02-12 02:03:06 +0000
commit2c55e121c22601d365aa353cfa39ee856770855c (patch)
tree0af68cb64d2e0e28542872589b3083b0fbbaec21 /src/gui/math3d/qmatrix4x4.cpp
parent121ad4c22f55be831105943ba11a4ff51b732698 (diff)
QMatrix4x4: deprecate operator*(QVector3D, QMatrix4x4)v6.1.0-alpha1
The operation is sketchy for a number of reasons: 1) Mathematically, it doesn't make sense. The code interprets the QVector3D as a point, extending it with w=1, and uses it as a row vector. But similarly, the vector could be intepreted as a directional vector, with w=0. No semantic is "better" than the other. 2) QMatrix4x4 is not meant to be post-multiplied. Granted, one could use a QMatrix4x4 as arbitrary storage for 16 floats, but QMatrix4x4 builds itself to be always *pre* multiplied (e.g. translate changes the 4th column, not the 4th row). We can keep post multiplication for the general case if we do it against a QVector4D, but I don't feel that we should support it also for QVector3D. [ChangeLog][QtGui][QMatrix4x4] The multiplication operator (operator*) between a QVector3D and a QMatrix4x4 has been deprecated. User code needs to extend the QVector3D to a QVector4D first (by specifying the intended w coordinate), and then multiply the QVector4D by the matrix. Change-Id: I41b64d8ab7eb6126dc4c49fe29cf3f1b7afc7987 Reviewed-by: Edward Welbourne <> (cherry picked from commit 654a2164994974639e62f9d388408ed559b797a3) Reviewed-by: Qt Cherry-pick Bot <>
Diffstat (limited to 'src/gui/math3d/qmatrix4x4.cpp')
1 files changed, 5 insertions, 3 deletions
diff --git a/src/gui/math3d/qmatrix4x4.cpp b/src/gui/math3d/qmatrix4x4.cpp
index 591809df31..947af641d1 100644
--- a/src/gui/math3d/qmatrix4x4.cpp
+++ b/src/gui/math3d/qmatrix4x4.cpp
@@ -627,16 +627,18 @@ QMatrix4x4& QMatrix4x4::operator/=(float divisor)
#ifndef QT_NO_VECTOR3D
\fn QVector3D operator*(const QVector3D& vector, const QMatrix4x4& matrix)
\relates QMatrix4x4
+ \obsolete Convert the QVector3D to a QVector4D first, then multiply.
Returns the result of transforming \a vector according to \a matrix,
- with the matrix applied post-vector.
+ with the matrix applied post-vector. The vector is transformed as a point.
\fn QVector3D operator*(const QMatrix4x4& matrix, const QVector3D& vector)
\relates QMatrix4x4